The subject matter described and/or illustrated herein relates generally to cables, and more particularly, to cables having twisted pairs of insulated conductors.
Some known data communication cables include pairs of insulated conductors that are twisted together to form a balanced transmission line. Such pairs of insulated conductors are commonly referred to as “twisted pairs.” One example of a data communication cable includes multiple twisted pairs that are bundled and twisted, or cabled, together and covered with a jacket. Known problems with cables having twisted pairs include crosstalk. For example, when the twisted pairs within a cable are closely placed, electrical energy may be transferred between two or more of the twisted pairs within the cable. Further, crosstalk may occur between a twisted pair within a given cable and other items outside the cable, which is commonly referred to as “alien crosstalk”. For example, alien crosstalk occurs when signal current in a twisted pair of one cable couples with a twisted pair of another cable. Crosstalk may increase the signal-to-noise ratio (SNR) and/or bit error rate (BER) of data communication cables.
Various cable designs have been used to attempt to reduce crosstalk and meet industry standards. Some cables include a central separator or filler for separating twisted pairs from each other and/or adding structural stability to the cable. Separation of the twisted pairs from each other may reduce the amount of crosstalk between the twisted pairs. However, the central separator or filler may undesirably increase a diameter of the grouping of twisted pairs within the cable, which may cause the twisted pairs to extend closer to other items outside the cable. Moreover, the central separator or filler adds to the construction costs and weight of the cable. The central separator or filler may also add more fuel in the case of fire, thus reducing or eliminating the ability of the cable to meet required fire safety standards.
Another attempt at reducing crosstalk includes positioning a filler between the twisted pairs and the cable jacket. The filler increases the distance between the twisted pairs and the jacket, thereby increasing the distance between the twisted pairs and other items outside the cable, such as a twisted pair of another cable. But, positioning a filler between the twisted pairs and the cable jacket may result in a cable having an oblong shape. Oblong cables may be more difficult to handle and/or may not fit through conventional circular cable openings within walls or panels through which the cable is intended to be fed.
Accordingly, some of the problems with at least some known data communication cables include an undesirably high amount of crosstalk between twisted pairs within the cable and/or between the twisted pairs of the cable and other items outside the cable.